2. DNA Molecule – Double Helix (twisted ladder) Watson and Crick Uprights – Sugar and Phosphate (Same in all DNA) “Rungs” – Pairs of nitrogen containing bases (there are only four) Adenine (A)Thymine (T) Guanine (G) Cytosine (C)

4.  Genes  “Genetic Junk” (variability)  Alec Jeffries – in England (1984)

5. Genes Non-coding regions (“Genetic Junk”

6.  Short Tandem Repeats (STR) (ATTG ATTG ATTG ATTG ATTG)  LOT’s of variability  Relatives are closer in their STR’s (Mom/Dad)  Lot’s of chance for mutation.  Pieces of DNA can be cut out and copied (multiplied) by PCR (small samples work

7.  CODIS has identified 13 regions that show big variability  The key is in the multiplied effect of the rarity of a given STR

9.  A Brief Animation A Brief Animation 2:25

11.  I A  I B  I O  As a result, the possible allele combinations are…

12.  I A I A & I A I O  I B I B & I B I O IAIBIAIB  I O I O  Which both result in type A blood  Which both result in type B blood  Which results in type AB blood  Which results in type O

13.  If you have the A antigen, you are type A  If you have the B antigen, you are type B  If you have both antigens, you are type AB  If you have neither antigen your are type O

14. BLOOD TYPEANTIGEN AANTIGEN BANTIBODY AANTIBODY B AYNNY BNYYN ABYYNN ONNYY

15.  Ethnicity and ABO bloodtype Ethnicity and ABO bloodtype

16.  Blood samples can be tested for antigen / antibody reactions to determine type.  Rh is another protein (Rhesus)  About 85 % of people have it (+)  The other 15% don’t (-)